[1] Univ South Wales, Fac Life Sci & Educ, Alfred Russel Wallace Bldg, Pontypridd CF37 4AT, M Glam, Wales
[2] Univ Hosp Wales, Dept Anaesthet, Cardiff, S Glam, Wales
[3] Univ Hosp Wales, Dept Surg, Cardiff, S Glam, Wales
[4] Kings Coll London, Dept Cardiovasc Surg, London, England